Cartridge heater



March 21, 1967 R. L. SIMMONS CARTRIDGE HEATER Filed June 16, 1964 30 INVENTOR, )Z55/mand l. S/)Wwons United States Patent O M 3,310,769 CARTRIDGE HEATER Ray L. Simmons, Hemet, Calif., assigner to Rama Corporation, San Jacinto, Calif., a corporation of Califoi-nia Filed June 16, 1964, Ser. No. 375,519 Claims. (Cl. 3138-241) This invention relates to an improved cartridge heater construction and the method of making the same.

Electric cartridge-type heaters have rbeen used in many Of those `arts where heat energy is required or desired. rlhe ordinary cartridge-type heater involves, generally, an elongate core of insulating material, `a coil of resistance wire wound about the core, an elongate tubular metal case or sheath arranged about the core and the resistance wire in insulated spaced relationship therefrom and a pair of conductors suitably fixed to or connected with the ends of the coil of resistance wire and projecting axially from one end of the case and adapted to be connected with a suitable power source.

The case lis suitably sealed at its opposite ends and about the conductors extending axially therefrom.

The art of cartridge heaters of the gener-al character referred to has become highly developed, with respect to the structure employed and the methods employed in their manufacture.

The resistance wire in such cartridge heaters is frequently extremely tine and delicate. The conductors supplying current to the resistance wires, which are exposed and must connect with .a suitable power source, must be of considerably greater cross-section and greater strength than the resistance wires. Accordingly, in the ordinary cartridge heater, a suitable mechanical connection must be made between the small or light resistor or resistance wire and the heavier conductors. Several means and/or methods of connecting these parts have been provided and will be set forth in the following.

The eiciency of cartridge-type heaters is materially affected by the proximity of the resistance wire from the inside surface of the casing. The closer the said wire is to the casing, the more effective is the heat transfer therebetween, when the heater is energized. Accordingly, the resistance wires are arranged as close as is possible to the casing, with-out resulting in shorting out of the construction.

Further, when the resistance wire is e-nengized and heated, the wire becomes soft and more fragile and due to the coefficient of expansion of the material from which it is established, it extends and would, if unsupported, become slack and free to shift into a position where a short might occur.

In order to safely arrange the resistance wire in a cartridge-type heater in close and eicient relationship with the case of the heater, and to provide the said wire with proper support, the prior `art has developed structures wherein the annulus between the casing and the core, with the resistance wire wound about it, is filled with a suitable ller of insulating material, which filler material serves` to hold and support the core and the wire assembly in xed, predetermined or desired position with respect to the case.

The most economical and practical filler material is magnesium oxide, which material is, lduring the manufacture of cartridge heaters, poured or otherwise deposited in the annulus lbetween the case andthe core assembly and is Ithen compacted about the assembly by swaging the case inwardly towards the core assembly.

In addition to the foregoing, the art provides cores of compacted magnesium oxide, which cores are partially tired so that they can be suitably worked upon and lwould be urged apart.

3,310,769 Patentedv Mar. 2l, 1967 handled during the assembly of the constructions, but such that when the cases are swaged, drawn, rolled or otherwise worked upon to compact the magnesium oxide ller, the cores will initially crumble and thence recompact about the adjacent structure and parts and `become an integral mass with the compacted ller. l

When a case is swaged, or otherwise worked upon to compact the ller, it is fed longitudinally through a suitable forming -head which reduces the diameter of the case. This swaging or case-forming operation necessarily results in elongation of the entire structure. If a rigid, brittle, ceramic core were to be employed, the core would fracture and the resulting sections or fragments thereof This would result in a core structure replete with open cracks, crevices, and the like. Further, the light Iand fragile resistance wire wound about the core would be shifted axially thereon and in such a manner as to create a short circuit or a break in the wire. The provision of a compactible core eliminates the establishment or creation of such conditions and/or problems.

It will be apparent that the ends of the resistance wire occur at the opposite ends of the core. Since the conductors project from and are accessible at one end of the cartridge or case, the end of the resistance wire remote from the said one end of the case must be extended longitudinally of the structure to the said one end thereof, or the conductor related thereto must be extended longitudinally of the construction to the end of the case -at which its related end of the 4resistance wire terminates.

In either event, the core must be provided with a longitudinal opening through which an end of the resistance wire or a conductor can be engaged, during assembly, to permit making up of the desired connection between the said conductor and its related end of the resistance wire.

Due to the ne and delicate nature of resistance wires, and due to the elongation or drawing of the construction during swaging or forming of the core, the resistance wire cannot ordinarily be extended through the core as it would be stretched and broken lduring the swaging operation. Due to the heavy and strong nature of the conductors, it is common practice to extend a conductor through the core to connect with the end of the lresistance wire remote from the end of the construction from which the conductor projects, as the conductor is not subject to be adversely affected during the sw-aging of the construction.

As the art has developed, it has become common practice to make heaters in different sizes, the several sizes being made up kof one, two, three or more standard (minimum) sized core assemblies arranged in end to end relationship and engaged in a single case of suitable longitudinal extent. The adjacent core assemblies are suitably connected in parallel with a pair of like elongate conductors which extend in spaced parallel relationship through the several aligned core assemblies, or in series yby means of a plurality of short pin-like conductors engaged with .and extending between adjacent cores.

This has led to the standard practice of providing cores having a pair of longitudinal conductor-receiving openings and the practice of establishing structures wherein the pair of conductors are of equal length and are coextensive with the cores, even though the heater may include but one core assembly and one end of the resistance wire connects with its related conductor at or adjacent the end of the heater from which the conductors project. This practice has several advantages, one being the fact that the excess conductor stock provides a stronger and more rigid mounting or foundation for the conductor. Another advantage resides in the fact that the conductor occupies aerox/ea its related opening in the core and provides for uniform or even reduction and compaction of the core assembly during the swaging of the construction.

The ends of the casing are normally closed by means of disc-shaped closures or plugs about which the casing is swaged into tight sealing engagement. One of the closure means is provided with openings through which the conductors extend and in which the said conductors are suitably sealed.

The foregoing sets forth the development of the art and the typical structure and method of manufacture of cartridge-type heaters presently provided by the art.

The principal difficulty with the standard cartridge heater construction set forth above resides in the connecting means employed to connect the ends of the resistance wires, at the opposite ends of the cores, to their related conductors extending through the cores.

Attempts have been made to extend the ends of the resistance wires radially inwardly at the ends of the cores and to solder the said ends of the wires to their related conductors. This practice has met with little success since such connections must be made up before swaging or otherwise reforming the construction and cannot be advantageously established so as to withstand and accommodate resulting elongation of the constructions.

Another connecting means that has been employed with some success consists of inserting end portions of the resistance wire in their related conductor lreceiving openings or passages, prior to engagement of the conductors therethrough and then urging the conductors through the openings so as to establish sliding linear contact with the end portions of the wires. Often the ends of the wires are pulled or broken off during insertion of the conductors, or are subsequently broken when the constructions are swaged and drawn or extended. It is asserted that in such a construction the initial fit between the conductors and the end portions of the resistance wires need not be snug or tight, but can be rather loose, prior to swaging of the construction, and that upon swaging the construction, the said elements are urged into tight fixed connection with each other. While this may often be the case, it is also frequent that upon swaging the construction, the core or insulating material is forced between the resistance wires and the conductors in such a manner as to prevent a positive connection therebetween.

Yet another connecting means provided by the prior art consists of an elongate contact strap in each opening in the core. Each strap is provided with a radially outwardly projecting tab at its end to which the related end of the resistance Wire is suitably fixed. When the conductors are engaged through the openings they contact the straps. While this means is not subject to being broken during the reforming and compacting operation, the electrical connection is subject to being interrupted by the flow or shifting and subsequent compaction of insulating material between the conductors and the straps.

An object of my invention is to provide a novel cartridge heater construction of the general character referred to and a novel method of making the same.

Another object of my invention is to provide a heater construction of the character referred to having novel coupling means for establishing electrical contact between the ends of the resistance wire or coil, about the compactible core and their related conductors, extending longitudinally through the core.

It is an object of the present invention to provide a novel malleable metal coupler having an axially extending collapsible conductor-receiving sleeve portion adapted to slidably receive a conductor and to thereafter be urged into tight uniform contacting engagement thereabout, when the construction is swaged or otherwise reformed or worked upon to compact the core and filler thereof.

A further object of this invention is to provide a coupler of the character referred to having a laterally projecting contact tab portion at one end of the sleeve portion to cooperatively engage and contact with a related end of a resistance coil.

Yet another object of my invention is to provide a novel core construction to cooperatively receive and support a pair of conductors, a pair of couplers as provided by this invention, and a coil of resistance wire, in predetermined relationship.

It is an object of this invention to provide a novel core assembly for a cartridge-type heater which is such that a plurality of like cores can be advantageously assembled in end to end, abutted, engagement with each other and cooperatively engaged with a suitable pair of conductors and in a single case, in accordance with general practice.

A further object of my invention is to provide a novel construction of the character referred to which is economical to produce and a construction Which is highly effective and dependable in operation.

The various objects and features of my invention will be fully understood from the followingdetailed description of typical preferred forms and applications of my invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is an isometric view of a cartridge-type heater embodying the present invention;

FIG. 2 is a longitudinal sectional view taken as indicated by line 2 2 on FIG. l;

FIG. 3 is an isometric view of the core construction that I provide;

FIG. 4 is a longitudinal sectional view taken as indicated by line 4-4 0n FIG. 3;

FIG. 5 is an end view taken as indicated by line 5-5 on FIG. 4;

FIG. 6 is an isometric view of my new coupler;

FIG. 7 is a sectional view of a portion of my new construction showing certain parts thereof in one stage of assembly;

FIG. 8 is a view similar to FIG. 7 showing the parts in another stage of assembly;

FIG. 9 is a View similar to FIGS. 7 and 8 showing the parts in yet another stage of assembly;

FIG. 10 is a view taken as indicated by line 10-10 on FIG. 9;

FIG. l1 is a longitudinal view of my new cartridge, in one stage of assembly and having portions broken away to better illustrate the invention;

FIG. 12 is a view similar to FIG. 1l, showing the construction lbeing worked upon; and

FIG. 13 is 4a view similar to FIG. 6 showing a modified form of coupler.

The heater H that I provide and which is illustrated in the accompanying drawings includes, generally, an elongate cylindrical core C of insulating material, a coil of resistance wire W wound about the core, a pair of couplers A carried by the core :and connected with the wire or coil W, a pair of like elongate conductors B extending through the core and cooperatively engaged with the couplers A, an elongate, tubular, metal sheath or case D coextensive with and surrounding the core and the other parts related thereto, closure means E at the opposite ends of the core and a filler F in the core, between the closure means and about the core assembly.

The core C is an elongate unitary structure having a cylindrical side wall l0, at axially outwardly disposed end walls 11, a pair of laterally spaced parallel conductorreceiving openings or passages 12 extending longitudinally through the core, enlarged coupler receiving counterbores or sockets 13 at each end of each passage 12 and terminating in the core to dene at, axially outwardly disposed annular shoulders 14, and laterally and axially outwardly opening notches 15 in the end portions of the core establishing communication with the counterbores or sockets 13.

The core C is formed of compacted magnesium oxide and is sufficiently fused so that the skin or exposed surfaces thereof are suiiiciently fused to provide the core with enough stability to be handled and manipulated during manufacture of the heater, but such that when the core is subjected to substantial forces and/or pressures, it will disintegrate or become reduced to granular form.

The coil or wire W is established of an alloy suitable for resistance heaters, such as Tophet-A, and is wound helically about the core in the manner illustrated in the drawing and so that its ends terminate at the opposite ends of the core.

The couplers A are unitary parts formed of malleable sheet metal, such as nickel. Each coupler A has an elongate tubular sleeve portion having a cylindrical side wall 21 and flat, axially outwardly disposed inner and outer ends 22 and 23. In the form of the invention illustrated, the sleeve portion 20 is split longitudinally, as indicated at 24.

The sleeve portion 20 is slightly less in outside diameter than the inside diameter of the sockets 13 and is substan tially the same inside diameter as the -outside diameter of the conductors. The sleeve portion 20 is less in longitudinal extent than the sockets 13. The said sleeve portions 20 of the couplers A are adapted to be slidably engaged in the sockets 13, with their inner ends 22 seated on the shoulders 14 in the sockets, fas clearly illustrated in FIGS. 7 through l0 of the drawings.

Only two couplers A are employed, one at each end of the core, and they are adapted to be related to the adjacent end of the coil wire W. The coupler at one end of the core is engaged in the socket 13 at' the end of the passage 12 and the coupler at the other end of the core Vis engaged in the socket 13 at the end of the other passage 12.

Each coupler further includes a laterally projecting coil wire eng-aging tab 25. The tab 25 projects radially outwardly from the other end 23 of the sleeve portion 2i) and projects into the notch 15 communicating with the socket 13 in which the coupler is engaged.

In the case illustrated in FIGS. 2 and 6 through 9 of the drawings, the tab portion of the coupler, is a longitudinally outwardly -opening U-shaped portion having a iiat base or seat 26 to receive the related end portion of the wire W and a pair of longitudinally outwardly projecting legs or tabs 27 adapted to be bent over the portion of the wire engaged on the base or in the seat and to thereby secure the wire in the seat and in positive electrical contact with the coupler. 4

It will be apparent that the portion 25 of the coupler being arranged in the notch 15 is removed from the end 11 of the core and does not present an obstruction which would prevent arranging the core in end to end butted engagement with another core or core assembly.

In FIG. l3rof the drawings, I have illustrated a coupler A with a different formof tab 25. In this form of the invention, the tab is a simple,'flat, lplate-like portion with a radially outwardly opening V-shaped notch 26 into which the end portion of the wirey W can be drawn to establish tight wedging and contacting engagement.

It is to be understood that in practice, the sleeve por tion of the couplers need not be split, but rather can be drawn or -otherwise formed, uninterrupted tubular portions having suiiiciently thin and soft ywalls to gain the desired collapsing affect when acted upon in a manner that will hereinafter be described.

The conductors B are simple elongate rods or wire stock of considerable size or weight. In practice, these members or parts can be established of nickel or a suitable alloy.

The rods B are entered into their related couplers A with whichthey establish sliding engagement and are thereafter shifted axially through the couplers and their Vrelated passages 12 in the core.

The rods or conductors B are substantially coextensive with the core and are provided with end portions or exrelationship. The end of the case adjacent that end of the core assembly from which the conductors B project is provided with a radially inwardly turned stop flange 31, which flange is established Iby a suitable spinning operation, or the like.

The closure means E at the end of the case from which the conductor extensions 30 project includes a plug 4t) of suitable insulating material, such as Teflon. The plug 40 has a pair of openings 41 through which the extension 30 of the conductors B are slidably engaged in sealing Contact. The plug 40 establishes seated stopped engagement with the liange at the end of the case.

The means E further includes an insulating disc 42, of lava, between the plug 40 and the adjacent end of the core. The disc 42 is provided with a pair of openings through which the conductors B extend.

The plug 40 and disc 42 are both such that they can be compressed or compacted into tight sealing engagement about the conductors, when the construction is swaged or reformed, as will hereinafter be described.

The closure E at the other end of the case involves a simple metal disc 43 slidably engaged in the case and fixed therein as by welding 44.

The closure means E and E set forth above are only illustrative of one form of closure means that can be provided. Accordingly, any other su-itable closure means can be employed without departing from the spirit of this invention.

VThe filler F is, for example, granular magnesium oxide and is deposited in the case and about the core asl sembly to fully occupy all the spaces and cavities in the construction.

In assembling the core assembly and the case, the plug 40 is rst engaged and seated in the case and the disc 42 is slidably engaged on the conductors and adjacent the related end of the core. The core assembly is then inserted into the case from the end thereof remote from the end in which the plug is arranged, so that the conductors extend through the openings 41 in the plug and the disc 42 abuts the plug.

When the above parts are thus assembled and properly oriented, the iiller F is introduced into the case and the structure is suitably vibrated so as to assure proper distribution and settling or packing of the ller material. When the structure is filled with filler, the closure plate 43 is engaged in its related end of the case and is suitably fixed, as by welding, therein.

After the construction is fully assembled, as set forth above, the structure is introduced into a swaging means, mill or press, which swages or otherwise reforms and` urges the walls of the case radially inward. When swaged or otherwise worked upon in a manner that requires that the case be worked upon in longitudinal progression, that end of the case in which the disc 43 is engaged is the lead end of the construction.

When the case is swaged in, in the manner set forth above, it first collapses the disc 43 slightly. As the swaging operation is continued, the iiller F is compacted and the core C is crushed or reduced to granular for-m and is recompacted in Iand about the wire W, couplings A and conductors B.

When the core is recompacted in the manner set forth above, the core materials surrounding the sleeve portions of the couplers urge and collapse the said sleeve portions int-o tight positive contact with their related conductors.

It Will be apparent that since the said sleeve portions of the couplers originally establish sliding engagement with their related conductors, filler material or core material cannot enter between the couplers and the conductors in such a manner as to prevent the establishment of the desired contact.

As the swaging or reforming operation is carried out and the heater construction is drawn or elongated, the various components, in advance of the swaging means, are free to shift axially and to adjust for any variations that m-ight develop.

At the end of the swaging or reforming operation, the disc 42 is compacted or compressed and the plug 40 is compressed and is caused to flow into tight sealing engagement with the flange of the case and about the conductors B, as clearly illustrated in the drawings.

While I have called for the core and filler as being established of magnesium oxide, it is to be understood that this material is only illustrative of one material that can be advantageously employed in my new construction.

It will be apparent that after the construction is completed, the core has been so acted upon that, for all practical purposes, it has lost its identification and combines with the filler F to establish an integrated compacted mass about and supporting the conductors B, wire W and couplings A.

From the foregoing, it will be apparent that I have invented a cartridge heater having novel and improved coupling means, a heater which is highly effective, dependable and durable, and a heater which is both easy and economical to manufacture.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any modifications and variations that may `appear to those skilled in the art and which fall within the scope of the following claims:

Having described my invention, I cla-im:

1. An elongate heater of the character referred to including an elongate resistance wire, a pair of elongate, straight, cylindrical conductors in spaced parallel relationship with each other and having portions adjacent the ends of the resistance wire, a coupler fixed to each end of the resistance wire and having a lsleeve portion slidably engaged about the portion of the conductor related thereto, a case about the wire, couplers and conductors and a compacted filler of dielectric material in the case and about said wire, conductors and couplers and holding the sleeve portions of the couplers in tight contact about the conductors, said conductors having end portions projecting from one end of the case.

v2. A heater of the character referred to including an elongate resistance wire coil, a pair of elongate, straight, cylindrical conductors extending freely and longitudinally through the coil in spaced parallel relationship with each other, a coupler fixed to each end of the coil, one coupler having a sleeve portion slidably engaged about one conductor and the other coupler having a sleeve portion slidably engaged about the other conductor, an elongate tubular case coextensive with and surrounding the coil and a filler of dielectric material compacted in the case about the coil, conductors and couplers, and holding the sleeve portions of the couplers in tight engagement about the conductors, said conductors having end portions projecting axially from one end of the case.

3. A cartridge heater ofthe character referred to including, an elongate compactible core of dielectric material, an elongate resistance wire supported by the core at the exterior thereof and having an end portion at each endrof the core, a coupler fixed to each end of the wire having an elongate longitudinally split sleeve portion on an axis parallel with the longitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged through the sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly from one end of the core, an elongate cylindrical tubular case surrounding the core, wire and inner end portion of the conductors in predetermined spaced relationship, closure means sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compactible granular dielectric material compacted in the case and Iabout the core, wire, couplers and conductors.

4. A cartridge heater of the character referred to including, an elongate compactible core of dielectric material, an elongate resistance wire engaged about and supported by the core and having an end portion at each end of the core, a coupler fixed to each end of the wire and having an elongate collapsible sleeve portion on an axis parallel with the longitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged through the sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly f-rom the core, an elongate tubular case surrounding the core, Wire couplers :and inner portions of the conductors in predetermined spaced relationship, closure means sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compactible granular dielectric material in the case and about the core wire, couplers and inner portion of the conductors, said compactible core and filler being compacted about the wire, couplers and conductors and to urge and hold the sleeve portions of the couplers in tight engagement about the conductors.

5. A cartridge heater of the character referred to including, an elongate core of compacted granular dielectric material, an elongate resistance wire supported by the core and having an end portion at each end of the core, a coupler fixed to each end of the Wire and having an elongate longitudinally split sleeve portion on an axis parallel with the longitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged through the sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly from the core, an elongate tubular case sur-rounding the core, wire and inner portions of the conductors in predetermined spaced relationship, closure means sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compacted granular dielectric material in the case and about the core, wire, couplers and conductors, said sleeve portions being urged into tight contact about the conductors by said compacted material.

6. A cartridge heater of the character referred to ncluding, an elongate core of compacted granular dielectric material, an elongate resistance wire engaged about and supported by the core and having a radially inwardly turned end portion at each end of the core, a coupler fixed to each end of the wire and having an elongate longitudinally split sleeve portion on ian axis parallel with the Ilongitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged through the sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly from the core, an elongate, cylindrical tubular case surrounding the core, wire and conductors in predetermined spaced relationship, closure means sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compacted granular dielectric material in the case and Iabout the cornpacted core, wire, couplers and conductors, said compacted dielectric materials holding the said sleeve portions in tight contact engagement about their related conductors.

7. A cartridge heater of the character referred to including, an elongate compactible core of granular dielectric material with a pair of spaced parallel longitudinal conductor-receiving openings having coupler receiving sockets at their ends and having laterally and axially outwardly opening notches communicating withthe sockets,-

an elongate resistance wire wound helically about and supported by the core and having a radially inwardly turned end portion at each end of the core, a coupler with a laterally projecting radially and normally axially outwardly opening U-shaped tab portion crimped about and xed to each end of the wire and arranged in a notch in the core, each coupler having an elongate collapsible sleeve portion engaged in the socket related to the notch in which its tab portion is arranged and on an axis parallel with the longitudinal axis of the core and concentric with its related passage, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the passages'in the core and each slidably engaged through the sleeve portion of the coupler related thereto, and outer end portions extending longitudinally outwardly from the core, an elongate, cylindrical tubular case of malleable metal surrounding the core, wire and conductors in predetermined spaced relationship, compactible closure means slidably engaged in and Sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a ller of compactible granular dielectric material in the case and about the core, wire, couplers and conductors, said case being swaged longitudinally and radially inwardly whereby the ller and core are compacted and hold the Wire,'couplers and conductors in xed position and said sleeve portions tight about said conductors.

8. A cartridge heater of the character referred to including, an elongate compactible core of granular dielectric material with a pair of spaced parallel longitudinal conductor receiving openings having axially outwardly openings coupler receiving sockets at their ends and having laterally and axially outwardly opening notches communicating with the sockets, an elongate resistance wire wound helically about and supported by the core and having a radially inwardly turned end portion at each end of the core, a coupler with a laterally projecting malleable tab portion crimped -about and xed to each end of the wire and arranged in a notch in the core, each coupler having an elongate collapsible sleeve portion engaged -in the socket related to the notch in which its tab portion is arranged and on an axis parallel with the longitudinal axis of the core and concentric with its related passage, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the passages in the core and each slidably engaged through the sleeve portion of the coupler related thereto, and outer end portions extending longitudinally outwardly from the core, an elongate, cylindrical, tubular case of malleable metal surrounding the core, wire and inner portions of the conductors in predetermined spaced relationship, compactible closure means slidably engaged in and sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compactible granular dielectric material in the case and about the core, wire, couplers `and conductors, said case and compactible core and filler being compacted about the wire, couplers, and conductors 'and to urge and to hold said parts in predetermined fixed relationship with the sleeve portions of the couplers held in tight engagement about the conductors.

9. A cartridge heater of the character referred to including, an elongate compacted core of granular dielectric material, an elongate resistance wire engaged about and supported by the core and having an end portion at each end of the core, a coupler of malleable metal fixed to each end of the wire and having a bifurcated tab portion receiving and establishing tight contact with its related end portion of the wire and having an elongate collapsible sleeve portion on an axis parallel with the longitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged throughthe sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly from the core, an elongate tubular case surrounding the core, wire and inner end portions conductors in predetermined spaced relationship, compacted closure means sealing the ends of the case and through one of'which the outer end portions of the conductors extend, and a filler of compacted granular-dielectric material in the case and about the core, wire, couplers and conductors.

10. A cartridge heater of the character referred to including, an elongated compacted core ofv granular d-ielectric material, an elongate resistance wire engaged about and supported by the core and having an end portion at each end of the core, a coupler related to each end of the wire having a U-shaped tab crimped about its related end portion of the wire and having an elongate longitudinally split sleeve portion on an axis parallel with the longitudinal axis of the core, a pair of elongate, straight, cylindrical conductors with inner end portions extending longitudinally through the core and each slidably engaged through the sleeve portion of one of the couplers, and outer end portions extending longitudinally outwardly from the core, an elongate tubular case sur rounding the core, wire and conductors in predetermined spaced relationship, closure means sealing the ends of the case and through one of which the outer end portions of the conductors extend, and a filler of compacted granular dielectric material in the case and about the core, wire, couplers and conductors, said compacted core and ller urging and holding said sleeve portions in tight contact about their related conductors.

References Cited by the Examiner UNITED STATES PATENTS 2,428,900 10/1947 Wiegand 29-15564 .2,817,068 12/1957 sehwing 339-221 2,831,951 4/1958 Desloge 3355-241 2,853,765 V9/1958 wemhoener 29-155.65 2,947,842 s/1960 Reek 3355-322 X Y 3,080,543 3/1963 Boggsl 33e-273 3,171,015 2/1965 Grindle 219-523 x 3,185,762 5/1965 shew 174-71 3,217,279 11/1965 Boggs 338-239 3,252,122 5/1966 Baxter 338-271 RICHARD M. WOOD, Primary Examiner.

V. Y. MAYEWSKY, Assistant Examiner. 

1. AN ELONGATE HEATER OF THE CHARACTER REFERRED TO INCLUDING AN ELONGATE RESISTANCE WIRE, A PAIR OF ELONGATE, STRAIGHT, CYLINDRICAL CONDUCTORS IN SPACED PARALLEL RELATIONSHIP WITH EACH OTHER AND HAVING PORTIONS ADJACENT THE ENDS OF THE RESISTANCE WIRE, A COUPLER FIXED TO EACH END OF THE RESISTANCE WIRE AND HAVING A SLEEVE PORTION SLIDABLY ENGAGED ABOUT THE PORTION OF THE CONDUCTOR RELATED THERETO, A CASE ABOUT THE WIRE, COUPLERS AND CONDUCTORS AND A COMPACTED FILLER OF DIELECTRIC MATERIAL IN THE CASE AND ABOUT SAID WIRE, CONDUCTORS AND COUPLERS AND HOLDING THE SLEEVE PORTIONS OF THE COUPLERS IN TIGHT CONTACT ABOUT THE CONDUCTORS, SAID CONDUCTORS HAVING END PORTIONS PROJECTING FROM ONE END OF THE CASE. 